1. Field of the Invention
The present invention relates to a method for fabricating a mold that is used in fabricating a semiconductor integrated circuit and a flat panel display.
2. Discussion of the Related Art
A general integrated circuit and a flat panel display include a plurality of electrical circuits formed by a plurality of thin films made of a semiconductor material, an insulation material, a conductive material, and a filter material. Some of the plurality of thin films are patterned on a substrate. A patterning process using an etching mask (i.e., resist pattern) provides the patterned thin film. The resist pattern is formed by coating a resist material to an etched thin film, exposing the resist material, and developing the resist material.
The exposure process requires an exposure mask and exposure equipment to selectively expose the resist material. Thus, an additional handling step (i.e., arranging the exposure mask) is performed. Accordingly, the patterning process of the resist material including the exposure process has complex processing orders. Therefore, the yield rates of a semiconductor integrated circuit chip and the flat panel display can be compromised. In addition, since the prices of the exposure mask and the exposure equipment increases as desired the pattern requires more accuracy and the pattern area becomes larger. As a result, the patterning process, including the exposure process, increases the fabricating costs of the semiconductor integrated circuit chip and the flat panel display.
In order to solve the above problems, an IPP (In-Plane Printing) method without an exposure process is suggested. The IPP method forms a patterned thin film by transferring a desired pattern to a pattern object thin film. In addition, the IPP method can form a resist pattern by transferring the desired pattern to a resist material using a mold. The mold includes a resilient material where detailed patterns are depressed/stamped.
The mold is prepared by a related art fabricating method as shown in FIGS. 1A and 1B. Referring to FIG. 1A, a thermally cured resin 15 such as PDMS (polydimethylsiloxane) is formed on a master substrate 111 where a first pattern 13 is formed. The master substrate 11 is formed of silicon or glass and the first pattern 13 is formed of one of inorganic materials, such as silicon dioxide, silicon nitride, and metals and organic materials, such as a resist and a wax.
The resin layer 15 on the master substrate 11 is solidified by heat. Molecular chain of the PDMS in the resin layer 15 not solidified by the heat is released to a surface of the resin layer 15 contacting the master substrate 11. This is to maintain the surface energy of the resin layer 15 at a constant value. In other words, the resin layer 15 has only a constant surface characteristic (i.e., a lipophile property).
As shown in FIG. 1B, the thermally cured resin layer 15 is separated from the master substrate 11. The separated resin layer 15 has a recess 19 on the lower surface thereof, which is formed by the shape of the first pattern 13. Accordingly, the resin layer 15 having the recess 19 is used as a mold 17 to pattern a pattern object thin film or a resist material.
However, the IPP patterning method requires a mold having a different surface energy depending on the material of the pattern object thin film, the process condition, and the desired pattern. In order to satisfy the requirements of the IPP patterning method, an additional handling may be performed to reform the surface of the resin layer (i.e. the mold) using an SAMS (Self-assembled monolayers). This surface reforming work contributes to the more complex fabricating method of the mold. Further, since the related art mold fabricating resin layer is solidified thermally in a single process, the interior material not solidified by heat (i.e., solvent) is released outside the resin layer to deform the shape of the mold.